Wave signaling system



Sept. 6, 1932. s. PRIECHENFRIED WAVE SIGNAL'ING SYSTEM Filed March 30, 1951 Mum/war a %w,

Patented Sept. 6 1932 UNITED STATES PATENT OFFICE GEORGE PRIECH ENFRIED, OF LONDON, ENGLAND, ASSIGNOR, IBY MESNE ASSlIGNMENTS, TO BRITISH RADIOSTAT CORPORATION, LIMITED, A'CORPORATION OF CANADA WAVE SIGNALING SYSTEM Application filed March 30, 1931, Serial No.

This invention is for improvements in or relating to wave signaling systems and is concerned with carrier-wave telegraphy or like signaling in which the signals consist of pulses of the carrier-wave energy of different lengths,'such as dots and dashes of the Morse code, with equal spaces between these pulses.

When itis desired to use carrier frequencies which are closely spaced it is necessary to use a receiver which is highly selective and has very low damping, such for example, as a tuning fork, a piezo-electric device, a retroactive thermionic valve circuit or a plurality of tuned circuits in cascade. With such a re-. ceiver the spacing period between signals is not of sufficient. duration (at least for dash signals) to allow the signals to die down to zero (or to effective zero) and consequently they may build up progressively to an excessive value. Also, since the dash signals may build up to a higher value than the dot signals owing to the longer timeperiod of the former, and the spaces are equal, the effective zero may be continually changing with respect to the actual zero condition, with the result of unreliable relay operation. It is the object of this invention to provide a system and apparatus whereby this difiiculty is avoided. t

The present invention comprises a carrierwave signaling system for Morse or like code telegraphy employing a highly selective receiver wherein means are provided at the transmitter and/or at the receiver for controlling automatically the maximum and/ or minimum amplitude values of the signals whereby they are respectively above and below the operating value of the device (such as a relay) operated by the signal.

The present invention also comprises a carrier-wave signaling system for Morse or like code telegraphy employing a highly selective receiver, characterized by the provision, at the transmitter and/or at the receiver, of signal controlling means that is operated automatically by the signal energy developed in the receiver, whereby the modulation variations of the signals shall be within a predetermined tuned circuits coupled in cascade. In Fig- 526,528, and in' Great Britain May 7, 1930.

range for operation of the modulation-signal reproducing devices.

The invention further comprises a receiver for modulated (e. g. interrupted) carrierwave signals, comprising the combination with a highly selective resonator, of controlling means, automatically operated by the output of the resonator, for varying the operation of the receiver according to the amplitude of this output.

The invention will now be described with reference to the accompanying drawing, illustrating diagrammatically two embodiments of the invention by way of example.

- In the drawing, 5

Figure 1 is a diagram showing controlling means in a receiving apparatus, and

Figure 2 shows a modifying system of transmission and reception employing different carrier frequencies for mark and space si 'nals.

eferring to Eigure 1 of the drawing, the received signals are applied to the terminals 10 of a highly selective resonator, either directly or through preliminary amplifying 7 and volume controlling devices. The high- 1y selective resonator may be of any desired kind and may comprise for example a piezoelectric crystal, a tuning fork, a retroactive thermionic valve system or a plurality of ure -1 a tuning fork is shown at 11 and is energized by means of a coil 12 connected in circuit with the input terminals 10. The mechanical vibrations of the tuning fork 11 resulting from the input signals produce corresponding electrical effects in a coil 13 which is connected in circuit with the primary winding of a transformer 14, the secondary winding of which is connected to the input of a thermionic valve 15 employed in this instance as a detector for the signals. The output circuit of this'valve includes a battery 16 and the rimary winding of another transformer 1? the secondary winding of which is connected to output terminals 18 which have connection to the recording or indicating instruments either directly or through suitable amplifiers.

A portion of the signal energy produced in reproducing device.

minlmum values of this range may be ad-' the coil 13 is Ied to the primary winding of a transformer 19, the secondary winding of which is shunted by an amplitude control ling potentiometer 20. One terminal of the secondary winding of this transformer is connected to the anode of a rectifying valve 21' of which the cathode is interconnected with the cathode of the detector valve 15. A smoothing choke 22 is connected in series between the adjustable tapping member of the potentiometer 20 and one terminal of high resistance 23 of which the other terminal is connected to the cathodes of the valves.

The input circuit of the valve 15 includes in" addition to the secondary winding of the transformer 14, a bias battery 24 and resistance 23.

In operation, a portion of the signal energy fed through the transformer 19 is rectified by the valve 21 and smoothed by the choke 22 and produces a potential across the resistance 23 corresponding in value to the amplitude of the received signals. This potential in conjunction with that applied by the battery 24 will provide the operatmg grid potential for the detector valve 15, which will be more or less negative according to the amplitude of the signals. Thus, when the signal energy produced in the coil 13 tends to build up to a high value the negative potential on the input electrode of the valve 15 is increased to reduce the effect of the signals and when the amplitude of the signals produced in the coil 13 are very small the potential on the control electrode of the valve 15 will be a minimum negative potential little more than that of the battery 24. Thus, the output of the valve 15 is controlled by the varying bias potential so that the signal will always be within the required amplitude range for operation of a relay or other The maximum and justed by means of the potentiometer 20 and the selected potential of the battery 24, and in order that any phase difference may be compensated a variable condenser 25 is provided in parallel with the resistance 23 and a variable resistance 26 is provided in parallel with the choke 22.

In another manner of carrying out the invention, the control of the amplitude signals at the receiver is effected at the. transmitter by using one carrier frequency for the marking signals and another carrier fre quency for the intermediate spacing signals. Thus, as shown diagrammatically in Figure 2 there is employed at the transmitter two oscillators 30 and 31 differing in frequency and the output of these is controlled by a signal key 32 such that the energy for the marking signals is obtained from one oscillator andthe energy for the spacing signal is obtained from the other oscillator. At the receiver the signals are applied to a broader tuned amplifier 33 the output of which is fed to coils 34 and 35 operating respectively two tuning forks 36 and 37. The tuning fork 36 has a resonant frequency corresponding to the carrier frequency of the marking signals and the tuning fork 37 is in resonance with the carrier frequency of the spacing slgnals. I

The mechanical. vibration of the tuning fork 36 produces corresponding electrical efiects in an outputcoil 38 connected to terminals 39 for application of the signals to the recording and reproducing instruments. On the tines of the tuning fork 36there are provided brass plates 40 between coils 41 connected in circuit with another coil 42 which is energized by the mechanical vibration of the tuning fork 37 during the spacing signals.

In the operation of this embodiment the energy building up in the output coil 38 due to the vibration of the fork 36 during marking signals is damped out by the eddy current device 40, 41, energized by the vibrations of the tuning fork 37 during spacing signals. Thus, in this embodiment the receiver "is reduced to zero condition before the commencement of each marking signal and the disadvantage of a varying zero or minimum signal efl'ect is avoided.

I claim:

1. Receiving apparatus for telegraphic signals comprising signal receiving means of low damping, the degree of damping of said means being insufiicient to prevent persistence of the signals so that the longer of the individual signal impulses fail to fall to their initial value following the passage of the signal, and means associated with said receiving means and responsive to the individual signal impulses for reducing the amplitude of the impulses to an extent proportionate to such amplitude.

2. Receiving apparatus for telegraphic signals comprising a mechanical rasonator of low damping, the degree of damping being insuflicient to prevent persistence of the signals so that the longer of the individual signal impulses fail to fall to their initial value before the succeeding signal arrives, and means associated with said resonator and responsive to the individual signal impulses to an extent proportioned to the amplitude of such impulses for materially reducing the difference in amplitude of the different impulses resulting from persistence.

3. Receiving apparatus for carrier wave telegraphy or like signals comprising the combination of a resonator ofhigh selectivity;

- by the signals.

4. Receiving apparatus for carrier wave telegraphy or like signals comprising the combination of a resonator of high selectivity such as to produce persistence of the signals whereby at least the longer of the individual signal impulses do not fall to their initial value during following spacing periods, and means automatically operated by the signal energy developed in the said resonator for controlling the amplitude value of the individual signal impulses delivered by the said resonator whereby the maximum and minimum values are always respectively above and below the operating value of a reproducing device to be operated by the signals.

5. Receiving apparatus for-carrier wave telegraphy or like signals comprising the combination of a resonator of high selectivity such as to produce persistence of the signals whereby at least the longer of the individual signal impulses do not fall to their initial value during following spacing periods, an amplifier for the signal output of the said resonator and an electrical circuit system energized from the output of the said resonator, said circuit system comprising a rectifier for the applied energy and a circuit for applying the resulting unidirectional effects to control automatically the amplitude value of the individual signal impulses delivered by the resonator to the said amplifier whereby the maximum and minimum values are always respectively above and below the operating value of a reproducing device operated by the output of the receiver.

6. Receiving appartus for carrier wave telegraphy or like signals comprising the combination of a highly selective resonator for received signals, an amplifier for the signal output of the said resonator, an auxiliary rectifier, means for feeding a portion of the output of the said resonator to the said rectifier for rectification thereby, means for smoothing the unidirectional output of the rectifier, and means for applying the smoothed output of the rectifier to control the said amplifier automatically in accordance. with the signal impulses delivered by the output of the said resonator to the said rectifier for rectification thereby, means for smoothing theunidirectional output of the said rectifier, means for adjusting the phase of the unidirectional electrical impulses in relation to the said amplifier, and means for applying the smoothed output of the rectifier to control the said amplifier automatically in accordance with the signal impulses delivered by the said resonator whereby the maximum and minimum values of the receiver output are always respectively above and below the operating values of the reproducing device operated thereby.

8. Receiving apparatus for carrier wave tele raphy orlike signals comprising the com ination of a highly selective resonator for received signals, an amplifier for the signal output of the said resonator, an auxiliary rectifier, means for feeding a portion 1 of the output of the said resonator to the said rectifier for rectification thereby, means for smoothing the unidirectional output of the rectifier, means for adjusting the phase of the unidirectional electrical impulses in relation to the signals, an impedance to which said impulses are applied, and means operated by the potentials developed across said impedance for controlling the said amplifier automatically according to the signal impulses delivered thereto by the said resonator, whereby the maximum and minimum values of the receiver output are always respectively above and below the operating values of the reproducing device operated thereby,

9. Receiving. apparatus for carrier wave telegraphy or like signals comprising a tuning fork resonator for marking signals, a second tuning fork resonator for spacing signals having a diflerent carrier frequency, damping means for the said tuning fork operated by the marking signals, and means operated by the resonator for the spacing signals for controlling the said damping means for the resonator of the marking signals.

In testimony whereof I afiix my signature.

GEORGE PRIECI-IENFRIED.

the said resonator, whereby the maximum and minimum values of the receiver output are always respectively above and below the operating value of the reproducing device operated thereby.

7. Receiving apparatus for carrier wave telegraphy or like signals comprising the combination of a highly selective resonator for received signals, an amplifier for the signal output of the said resonator, an auxiliary rectifier, means for feeding a portion of 

